Cisco Expands 40G Reach

In the race toward high-speed, next-generation carrier networks, doing more with less is a key challenge. For network equipment vendor Cisco, helping carriers meet that challenge requires innovative optical technology solutions, like IPoDWDM (Internet Protocol over Dense Wavelength-Division Multiplexing)

IPoDWDM, as the name suggests, supports carrying IP over Dense Wavelength-Division Multiplexing, or DWDM , fiber-optic networks without the need for costly, additional IP cross-connects or optical transponders.

To better capitalize on the technology’s potential, Cisco is now expanding its IPoDWDM 40 Gigabit-per-second (40Gbps) solution to work at greater ranges, with improved manageability.

The enhanced solution is part of the networking colossus’ strategy to gain more share in the carrier router equipment market, a segment that could be worth more than $11 billion.

“We think this is a very cost-effective solution from a number of dimensions,” Mike Capuano, marketing director for Cisco’s service provider routing and switching unit, told “You’re getting a 4x improvement in bandwidth. You don’t have to pay to operate, update and maintain extra components anymore. And you reduce your carbon footprint using less energy.”

Capuano explained that the way that packet networks used to be built is that generally a carrier would process traffic with a core router. That core router would admit traffic through a short-reach optical interface transponder, and if the traffic was going to have to travel a long distance to another core router, it would be typically go over an electrical cross-connect.

With IPoDWDM, transponders are no longer required, since that functionality is integrated into the core router.

“That eliminates shelves and shelves of gear as the transponders and cross connects are pretty beefy,” Capuano explained.

In its latest update to the technology, Cisco is effectively doubling the length of its transport to 2,000 km — an improvement that could reduce the number of times a packet needs to undergo regeneration, which Capuano described as taking a packet “from a photon to electrical and then back to a photon.”

“In general, the longer the packets stay as photons, the more cost-effective and reliable the network is versus … regeneration,” he said.

Another improvement is aimed at making the prospect of moving to adopt IPoDWDM — and merging data and transport carrier networks — less daunting. For some carriers, that means the prickly task of merging what traditionally had been the responsibilities of two different departments.

“If you look at a provider that has a more rigid data department and transport department, and a lot of them do, that has been a barrier,” Capuano said. “You’re integrating what had been in a separate box into the router.”

To help overcome that hurdle, Cisco created a virtual transponder that carves out the subsystem inside of a router, which it represents through an XML API. As a result, the API enables the transport department to manage the subsystem.

Looking ahead

Cisco isn’t the only vendor keen on using IPoDWDM as a way to help carrier reduce costs. Rival Juniper networks also sees the benefits of IPoDWDM.

“Integrated IP-optical DWDM networks have clear benefits in reducing the number of components in the network for providing end-to-end IP connectivity and routing,” Luc Ceuppens, senior director of marketing for Juniper’s high-end systems group, told

“Converged IP and DWDM networks provide significant benefits to service providers, since router-integrated transponders eliminate transponder shelves, thus providing both [capital expenditure] and [operating expenditure] savings,” he said. “In addition, standardized management interfaces provide end-to-end network monitoring and performance management.”

Both Cisco and Juniper also offer technology solutions for IPoDWDM that enable carriers to use their existing 10Gbps networks to transport 40Gbps traffic. Cisco’s Capuano explained that on the 40G interface for Cisco’s CRS-1 core router, traffic can be modulated onto a 10G optical wavelength.

“So you’d have 40G coming out of the CRS-1 and it would be squeezed down into 10G wavelengths, go into a DWDM system, and then a CRS-1 on the other side would demodulate that back to 40G,” Capuano said.

The move to 40Gbps with IPoDWDM uses the OC-768 optical standard that both Cisco and Juniper have been advocating for the past several years. The IEEE is currently working on a dual 40/100 Gigabit Ethernet (GbE) standard that could potentially replace OC-768. Cisco and
Juniper are both actively pursuing carriers for 100GbE trials, though actual production usage is still a few years away.

“Our current approach to core ‘long haul’ is OC-768, as that is the best technology available today and providers need that now,” Capuano said. “If you look at 100GbE, the standard is targeting June 2010, and we’re actively investing in 100GbE. But right now, adoption is on OC-768.”

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